But the wind hasn't kicked up over three rounds, and overnight rains have kept things soft, allowing shots to hit the green and hold, the way Thomas' 3-wood did from 310 yards out on the 18th hole.
Oosthuizen ran off four birdies on the front nine and made the turn at 4-under par, leaving him only three shots behind.
NOTES: Patrick Reed, who shot a 65 on Saturday, wore a red, white and blue ensemble that included the blue trousers he wore during the 2016 Ryder Cup, when the United States captured its first title since 2008. "I wish he was calling it", Thomas said of Miller, the longtime broadcaster, "just to hear what he would have said".
"Usually when you shoot even in a U.S. Open and you're one off the lead, you're not six down afterward", J.B. Holmes said.
He was at 12 under having hit his second shot on the par-5 18th just 47 yards from the pin.
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Thomas said he knew the putt was for a 63, and he told his caddie as they walked down the fairway, "Let's try to become a part of history". Subsequently, the leaderboard is crowded with low scores heading into the final round. The course has still been punitive enough to take a chunk out of the top three players in the world, all of whom missed the cut. There were five after Saturday's round. I have no idea what tomorrow is going to be like but I'm confident that I am prepared for whatever happens, whether something bad happens or something good happens.
Coming off a playoff loss to Ariya Jutanugarn last week in Canada, Thompson had six birdies and a bogey to reach 15-under 196.
Reed, who beat Rory McIlroy in the first singles contest at Hazeltine a year ago and was wearing the pants from his Ryder Cup uniform, said: "You always can take that fire from Ryder Cup and use it in other events". He rolled a long birdie putt off the sixth green and made bogey, and he dropped two more shots with three-putt bogeys.
"Today I felt really good, played really well". Every time I've been in majors so far I've put so much emphasis on them and tried so hard at them that I kind of got in my way.
"If somebody shoots nine-under from the top few then I'll have to shoot 10, I guess".
Sean Zak: Bold as this may seem, I'm going with Tommy Fleetwood. The first time he's playing in the final group in the final round on one of golf's biggest stages.
Kite says it looks as if the conditions at Erin Hills "are going to be a lot more challenging", but he doesn't think it will look like what happened 25 years ago. "And I can still beat my best finish at the US Open", said Leishman, referring to his 18th placing at Oakmont past year. On the back nine, a double bogey on the 10th and an 8 on the par five 14th with a wedge to the green for my third shot made me finish sixth to Jack Nicklaus, the victor.